How To Clean Hydraulic Brake Pistons - Tech Tuesday

Prevent "sticky pistons" by cleaning and lubing the pistons every time you change pads. We talk a bit about how the brake functions and walk through the cleaning procedure to help your brakes in the long run.
Questions or comments? Leave them below!
➤ Tools & materials used:
• PP-1.2 Hydraulic Brake Piston Press www.parktool.c...
• DOT fluid or Mineral oil ( use the same hydraulic fluid in your brake)
• Cotton swabs
• Isopropyl alcohol
➤ Fix It:
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• Visit our KZbin Channel: / parktool
• Visit the Repair Help section of Parktool.com: www.parktool.co...
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[@corkhead0]

I always wondered how hydraulic brakes self adjusted. It's beautifully simple. Great explanation!

[@adriansue8955]

I think they're simplifying the explanation here. Also have to remember the oil reservoir on the master cylinder, its open to the cylinder at the resting position, but closed off during motion. This means as the master cylinder returns, just before returning to rest the system becomes open and oil pressure is relieved; so the slave pistons don't get fully sucked back to where they started. At the same time, the flexing seal means there's preferential for the slave pistons to slip more in one direction than the other. Both things need to work together for the pad wear compensation.

[@qisxis]

@@adriansue8955 yes thanks so it is a two sided story.. The pressure side and the relaxing side. Nice to get more understanding

[@cebruthius]

@@adriansue8955 I think the way it works, is that the seal can also flex a bit in the other direction. Only when the master cylinder piston returns past the reservoir timing port, the caliper piston seals can relax to the middle position.

[@KarlenBell]

This was super informative! I always thought the pistons moved back because of the vacuum in the chamber when it is pushed out, but it was the seals that were doing the jobs all along~

[@oscarbloomer3979]

A 3mm Allen key in the calliper slot where the rotor is positioned will stop the pistons from popping out. (4mm Allen for Sram). This way all the pistons can be cleaned. If disassembling the calliper then this method is great for getting the pistons completely out to check the seals

[@edge24x]

I never knew this!! Amazing and extremely underrated comment.

[@punkybeerconsumer]

Another Tip: Keep an old set of pads around as a maintenance pad set. Allows you to push the pistons back in without damaging the piston faces if using a flathead screwdriver/chisel/etc.

[@moltam99]

Use plastic tire levers :)

[@punkybeerconsumer]

Ha. Good idea. I keep my plastic levers in the road kit. Have the Park metal levers that've never let myself down.

[@s31720]

Was wondering if it was necessary to invest in the parktool piston press that they use here. I tend to bodge it with my metal tyre levers and always scratch the surface.

[@butchgreene]

Simplest and least damaging is the box end of a cheap 10mm wrench. I say cheap because expensive ones have a huge width. Cheap ones will drop between the pucks. And if you have old Hayes post mount brakes, the box won't break the post

[@keatonalexander89]

@@s31720 I use a wooden paint stir stick. They are firm enough to do the job, soft enough not to damage the pistons. Stick one through the caliper and pull with both hands

[@PhoenixT1953]

2:43 *alcohol for our alcoholic friends*

[@nickmihai]

Funny guy! :))

[@Leviathandk]

I came to the comments for this

[@nicolasmasquerade]

Lol wanted, to write same thing ;)

[@1ignis]

..that is ethanol !. Surely a cheaper and better option would be isopropyl alcohol and save the ethanol for a G&T?

[@BPNX]

Could i also use regular brake cleaner or lighter fluid for the cleaning part?

[@mikecox7574]

Very well done guys. One item of note, if you have a Shimano brake with ceramic pistons do not use any metal tool to cycle the pistons. Also you have to be very careful to push on the center of a ceramic piston as to not get it sideways. With ceramic I will usually leave the old pads in to protect the piston while I cycle them.

[@David_SPN]

I made a mistake, I pressed too hard and the pison came out, I put it back on but it caught air. and after a while I started to lose the mineral oil from the Shimano hydraulic brake. Please help me and explain to me how to proceed to put the piston back so that I do not lose mineral oil again. Thanks!

[@ninjapyro9969]

@@David_SPN put it back and then bleed the brakes

[@HarveyLMiller21]

@@David_SPN You can't put the pistons back without losing the mineral oil or brake fluid. After cleaning the piston and placing it back you'll need to bleed the brake.

[@rodent]

what material is the back of the pad made of? metal. that tool is flat as a pad, so I guess is as safe as a pad to push pistons back.

[@oot-n-aboot]

This is fantastic! I've been changing my pads and aligning my rotors for years, but never thought to clean and lube the seals. Pesky seals! Thank you,

[@picuszesranej5891]

You guys are absolutely AMAZING, THE BEST. I LOVE YOU. Im kinda newbie and dumb about bikes and such. Especially whole brake system was kinda hard to understand for me, but i wanted to fix myself. I was reading some articles etc, few videos and it didnt help me at all.But every each one of your videos is so well made, nicely and easy explained.. Only thank to your videos, i got it all now. I fixed everything i needed. Simple, easy and compared to some services very cheap. Thanks so much. Amazing job, good luck fellas.

[@bkxc]

Solid info guys!

[@ed0078]

Excellent Park Tool®. We need more of these. Kudos to the graphic artist

[@elbobbitosmartito4185]

Another tip. Anti-bleed the breaks if the piston doesn’t quite go all the way in. Unscrew the bleed port on your break handle slightly and push the piston in a little bit. Let a couple drops of fluid out. A little goes a long way so don’t push too hard on the piston.

[@user-cx2bk6pm2f]

The illustrations and animated graphics are incredibly well done. Give that man a raise! 😀👍

[@karlbe8414]

Best explanation of a very common and eventual problem for most anyone. Great visuals!

[@jgbarre]

Had a sticky seal on my wife’s recumbent trike. Was able to unstick it with the help of your video. Thanks guys!

[@markjones7130]

That was a great presentation. Very detailed with cut away parts. I had squealing brakes but after 3 repeated pad/rotor cleaning and scuffing it still squealed. After your video I checked the pistons and found they moved very little and did not retract. Followed your procedures and now they move properly. Voila! The squealing is gone. Big thanks guys.

[@MichalSzul]

Before last piston push in I suggest cleaning oil from the piston surface as it will attract dirt and make it sticky again quite quickly.

[@joecanuck3751]

I'm also in the camp of after the cleaning process to remove excess oil with brake cleaner or alcohol so that dust won't collect.

[@hughjanus7354]

Agree, this will prevent unintentional oil transfer and pad/disc contamination.

[@RichardE221]

I thought I needed to replace my brake pads and rebleed the system after about 500 miles of mixed riding. I cleaned my pistons and they work like new! Thanks guys. This was the answer.

[@SarcoZQ]

Well done guys. Thanks to this video I was repair a lazy piston yesterday. Felt great knowing what to do and your enthusiasm works really well. Thanks again.

[@th_js]

Great tutorials guys! But mostly I just watch these for entertainment!

[@polishguywithhardtospellna8227]

It's Tomi again ;-p

[@briantrend1812]

Tomi Saaranen it sure beats watching todays politics ....but then its our duty to know what is happening out there because we live in dangerous times . I'm new to hydraulic brake calipers without the internet id be stuffed. its these dam pistons that confuse me . my shimano pistons from 2014 models are just plastic looking black ones without any rubber Orings? all the others iive seen have ceramic white pistons and rubber orings. so on striping the caliper and opening it I thought I may have lost the white ceramic ring part but no there isn't any white ceramic on this model just a black one?

[@educationalvideos4151]

I think this helped with a brake centering issue I was having. My rear wheel was almost rubbing on one side with more daylight on the other, but the rotor was centered in the caliper. After adjusting the caliper or pressing in pistons it would just happen again later. Today fixed the sticky piston on one side and now I see even daylight on each side. Maybe the better-moving side was squeezing out too much each time I tried resetting brake alignment, while the sticky piston wasn't out enough yet. I don't know if it would actually work that way, like I think it would have to almost slightly and temporarily bend the rotor from one side while braking for the piston to remain stuck out too much. I'm running thought experiments in my head while tired and I'm a maintenance newb anyway. Maybe I did something else that fixed the centering... but I think it was this.

[@marky26uk]

Best bicycle maintenance tutorials i've seen, thanks guys :)

[@wtfmimshag]

Great tips. Been working on bikes for how long and never saw an explanation for why one piston might want to move more than the other.

[@adriansue8955]

for me its more like, I've never seen an explanation for why they should want move in synch in the first place. There's no mechanical coupling between them, and fluid's going to take the path of least resistance. So in my mind is a miracle that they'd even be as close as they are.

[@akeluify]

@@adriansue8955 the fluid isn't taking any paths of least resistance, as the resistance is the same on both sides of the pistons. Theres the same amount of gap for the fluid behind each piston. So whats happening is even pressure is being applied to each of the calipers, its just up to the seal to bring it back after pressure taken off,

[@hughjanus7354]

@@akeluify "the resistance is the same on both sides of the pistons" ...in lab conditions when both pistons are brand new. And even then there will be differences resulting from how each seal interacts with each piston. Once they start picking up dirt these differences will increase and each side will retract differently.

[@jkamer2168]

Killer video, a huge step I've been neglecting. Sorry wifey...gonna be in the garage tonight!

[@Bjoggi308]

Best way that I have found to clean the pistons is to use a nylon tube brush. Then lube with mineral oil or brake fluid, then push back, clean, re-install.

[@82lostsoul]

Just done this exact procedure on my PITA SRAM Guide R brakes, best they’ve ever felt the 9 months I’ve had the bike!

[@MTBMOR]

Just did on my 4 pistion SLX brakes...I hope my feel as good on the trail as they do in the garage

[@alanlemap]

(glad it helped but) isn't that against SRAM manufacturers guidance, to NOT use dot fluid around the piston? I am wondering if the fluid would make the seal slide instead of GRIP and pull back, the way it should....? The reason is, I have pistons that don't retract enough after use, so they grip juts enough to stop the wheel spinning freely ...

[@kamilnaumowicz1635]

You guys sure "sealed" the deal with this video.

[@ajlong404]

Terrific job explaining how the pistons work and how to clean them. But, that seal clap and bark is everything! I had to watch the beginning of the video a couple more times. 😆😆

[@PeterKern63]

Great instructions, explanations (including graphics). Helped us getting hydraulic break pistons cleaned and brake pads replaced! Thank you!!

[@wallace8637]

I love this guy talk. Looong and simple at times.

[@fluffyfizzer]

Fantastic video! I’ve just performed this job after shying away from it for years! Thank you!

[@CW-up7xv]

Why not clean the Piston initially with rubbing alcohol, then go to using the mineral oil/ dot fluid when working the piston back and forth? Feel like alcohol does a better job initially removing the dirt...

[@45graham45]

I've heard it said that you shouldn't use oil (fluid) to clean the pistons. Reason: if you do then the seal won't have as much grip on (it slips) it which makes it more difficult for it to retract the piston. IPA or brake cleaning fluid should be used. Also, whilst preferable to clean the piston, just pushing them back without cleaning them occasionally isn't a problem , normally the seal just pushes the dirt off the piston.

[@sbrinton3]

Very informative on how to correct those sticky pistons. Thanks

[@alrocky]

3:36 Recommend you *_do not_* insert Q-tip into container but instead pour small amount of mineral fluid into small (Dixie) cup.

[@David_SPN]

I made a mistake, I pressed too hard and the pison came out, I put it back on but it caught air. and after a while I started to lose the mineral oil from the Shimano hydraulic brake. Please help me and explain to me how to proceed to put the piston back so that I do not lose mineral oil again. Thanks!

[@veejay2901]

​@@David_SPN you will have to bleed it from scratch.

[@14erGuy]

Thanks for making this fun to watch as well as informative! You guys are great. And it really helped that you talked about one caliper moving less than the other because I have this exact same thing going on. Thanks for the help! And I'm subscribing to this channel now.

[@vitrobenek3426]

Great video, very comprehensive. From my experience water and mild soap works better to remove both brake fluid and mineral out. Furthermore, I would also mention how the reservoir works and how it gets isolated by the master piston before pressure build-up. Many people still think adding more fluid to the system than intended will reduce the dead stroke.

[@billybass4189]

Nice tutorial, I have a lazy seal on my front brakes and now I'm Confident to tackle the problem.

[@joemichaelegan8214]

I’ve used some Pad grease as is used with Motor vehicle Brakes and I have improved feeling through the lever as well as the eradication of sticking Pads and noisy metallic scraping from the Cycles Disk Brakes.

[@MultiGreenGaming]

Woah, this video was uploaded the moment i sat down to clean my brakes, what a coincidence :O. Thank you very much very informative and fun tutorial!

[@MrTimmmers]

Brilliant video, I had a lazy seal, was really messing with my head until I watched this. Many thanks guys.

[@fernandolespade]

Muchas gracias por su aporte! Realmente se agradece, es simple y me parece que está muy bien explicado. Tanto la animación como el capiller recortado es de mucha ayuda para entender como funciona el sistema. Saludos desde Argentina. Comenzaré a seguirlos.

[@cstrike105]

Thank you for the info. Learned a lot on how to clean my disc brake pistons.

[@harry-eto]

You guys would make a dream team children channel hosts!

[@jimmycurry6115]

No one,,,, and I mean NO ONE!! has ever explained and shown what actually goes on inside a caliper like y'all did. I feel as if a light has finally been turned on in the braking department of my brain. Thank guys.

[@mrbarkeater1]

haha, after all that they never show successful endpoint where when you pull lever, both inboard and outboard pistons extend same amount. I would bet 99% of the hydro brakes out there operate with only one piston (for two pot caliper) doing most of the work. still, good video guys. keep up the good work

[@butchgreene]

Don't bet...try it. You'll be 100% right. With 4 piston pucks its even whackier

[@erikkjelland5719]

Frank zappa Making the magic happen. Loved the seal btw

[@3232groundhog]

Hell of a compliment guy. 👍

[@VanDungLe2510]

Wow, thank you so much :)) I've been told to use silicon grease to lube the piston. But know, thanks to you guys, i know that i can use brake oil to both clean and lube the piston (and also know how the system work too). P/s: i know with mineral oil is fine, but i don't think you should use the same method for DOT fluid braking system, cuz DOT oil is a little bit too harmful.

[@bobbyhempel1513]

I just got a new bike, my first set of hydraulic disc breaks so this is going to help allot.

[@MTBMOR]

I just did this and it fixed my brake rub....I have never had to do this in over 5 years of having disc brakes until now...Great Video

[@lukepatrick6196]

I dont even have disc brakes and I watched this

[@erikkjelland5719]

Dude, that is dank

[@nickmihai]

Dude, this is nice to know when you have that :))

[@twintyara6330]

Nice, you have eyes

[@jakeb1778]

Thanks for the video. I have brand new slx 4 piston brakes on my bikes. Despite lubing/working the pistons, one side is still uneven to the other(less them 1mm). At the end of this video you guys day to just leave the piston and center rotor between pads. Therefore having the caliper itself slightly off center to rotor. I've been told elsewhere to restrict overactive pistons and balance. Then align caliper to rotor... Wood really appreciate if you could elaborate

[@bendenisereedy7865]

Great explanation. Most people think the pistons slide in and out of the seals.

[@qisxis]

The calipers van Moof the valve nearest to where the fluid goes in from the hose , goes out more. The fluid to get to the other side have to go to a tiny hole and a longer way so you loose some brake pressure. I use one 0.10 mm gauge on one side of the disc and the pad and push the brake and set the bolts . This way have a correction from the slower piston and the brakepads are nicely parallel and not randomly adjusted by eye. I always try to see if both brakepads are hitting the disc at the same time. So the disc does not bend to one side. BTW sometimes when surfaces of the caliper or on the frame/fork is not flat the caliper can move while tightening the bolts. Then you have to use your eyes again

[@cavemancodeman9519]

amazing video!! i was just thinking, ok i know how to bleed Hydraulic brakes.. but what's actually inside? Cause something ain't right with mine. Good info thank you

[@hardtailshredder]

They cut apart a caliper for people to understand better. I love these guys

[@parsnips800]

Great information in this video. Thanks for taking the time to produce this .

[@LotsOfRobotsINC]

Thanks for your help. I just bought a maintenance stand so I can fix everything myself, with your help.

[@kenoliver8913]

My tip: Put ONE of the pads back in as a temporary stop to prevent pushing the piston out too far. Take it out and then clean your pistons.

[@David_SPN]

I made a mistake, I pressed too hard and the pison came out, I put it back on but it caught air. and after a while I started to lose the mineral oil from the Shimano hydraulic brake. Please help me and explain to me how to proceed to put the piston back so that I do not lose mineral oil again. Thanks!

[@HarveyLMiller21]

@@David_SPN Bleed the brakes. Once the piston falls out you can't prevent loss of fluid while air enters the system.

[@slashdoink2501]

I have a Shimano 4 pot piston from a mountain bike that’s less than 15 month old, I have explained to the bike shop that the outer bottom piston is not retracting all the way back and is causing intermittent disc rub at certain speeds which is quite annoying, they have had the bike once and said they have done a front brake service on it. I took this bike out and it is now worse than it was before. I have taken this bike back again but I don’t have much confidence of them fixing it.

[@LesssIsMore]

Great video but I'm confused. Were you using the right hand brake lever for the front brake? Isn't it the other way around?

[@JohnnieDorman77]

Guess the bike is set up for a left hander. Ha! Good thinking.

[@alanlemap]

Countries that drive on the right have front brake on the right. Opposite for GB AU NZ SA( and probably HK and JP...,)

[@lytleric]

I have a problem with my brake pistons sticking so I've been researching what to do. It makes sense to me why we need to clean the piston: to prevent debris from working its way back into the seal. However, Singletracks posted an article on cleaning brake pistons that specifically states "brake pistons should not be lubed. They should be cleaned." The article goes on to explain how to clean pistons using isopropyl alcohol. But in this video, you use mineral oil to clean the piston. Isn't that in effect lubing the piston, which is what the Singletracks article says NOT to do?

[@gcdcg4d]

Best explanation ever. Now we know what's going on!

[@robertdewar1752]

Nice diagram of how the seals work

[@buster.keaton]

Note that Shimano does not sell replacement pistons or seals. If your seal is leaking or the piston is cracked, you're buying new brakes. 😞

[@Alan-yu5vn]

great info, well done! just felt like this vid was made to entertain toddlers

[@ItsABarmcake]

Exactly what my pistons are doing on a used bike I bought. This might have saved me a trip to the bike shop!

[@yoavcooperberg4271]

Please do a tour of all the tools in the mk-278

[@jamesturner9481]

The very last bit might help me out, I have one side that moves a fair bit more than the other so moving the caliper should help. Crossed my mind to try that 👍👌☺️

[@Rebelscum985]

Awesome video. This is the kind of info that’s difficult to find. Thanks for making it easier for us!

[@aye5519]

Thanks a lot, that’s what i was looking for to fix my hydraulic break 👍🏻

[@btown8210]

This are superb tutorials/info! Thank you

[@haansworsie]

Tonight my friend and I replaced pistons and got brakes working good as new again. Super stoked 🖐️

[@johnnyfu509]

Never knew pistons could come out. I thought I broke something. Thank you guys for telling me I just screwed up and nothing broke.. Gonna need to put I back and re-bleed.

[@s31720]

Hey Johnny Fu, same thing happened to me. Did you just put the piston back in? I was surprised that there wasn't some sort of limit screw to stop them coming out.

[@johnnyfu509]

@@s31720 Yes sure did. Simply aim and slide it back in and of course do a full bleed and some more.

[@mywaveinwoodswoodperfumes]

nothing better than scientific explanation, massive thank you

[@genesioapretto5077]

you of the Park Tool are very well understood know what they do and the tools are appropriate

[@MaquinasDePalomitas]

You just gotta love these guys.

[@wlouisharris]

Very informative. Hydraulic disc brakes are a pain though. They stop with amazing precision but there are a number of components to maintain. The part I am having a problem with is reaching the pistons while I have the brakes compressed.

[@JasonTong]

Thanks guys... this cleared up alot of questions I had.

[@Piplodocus]

*thinks* I probably shoukd have watched this 5 years ago when it first came out! 😂

[@RochX-7]

This was not the video I intended to watch... but I'm glad I watched it. You guys are solid af. lmao :)

[@pminiger9278]

So working on your bike's brakes is a two person job! Awesome!

[@XavierBetoN]

You know the content will be heavily educational when you hear about seal sounds au au au au

[@paulsack9563]

Dropping knowledge like it's nothing. Thank you :)

[@Joseph_JoJo440]

Thanks for that. Couldn’t get my back wheel back in and had no idea why or how to adjust the brake pads (I knew where I was with v brakes). All sorted now!

[@markfletcher9791]

Ah Calvin.... you should have gone on with the line (2m45s) .... "We have DOT Oil, for our DOT friends. We have Mineral Oil for our Mineral Oil friends. And we have Alcohol for our Alcoholic friends".

[@b.s.adventures9421]

Good tips. I’ll be employing those at work soon. Thanks.

[@peglor]

Perfect until right at the end where they said to move the caliper if the brake pads remain uneven. Just hold back the active pad with a screwdriver or similar and pump the brake and it'll center up fine. It's a 'feature' of the more recent Shimano brakes unfortunately, causing wandering bite point - sorted in a couple of minutes every month or so as the pads wear.

[@audiofella5066]

The more i learn about hydraulic brakes the more I love my cable actuated BB7's!!!!!!

[@FollowThatDale]

Excellent as always. Thanks!

[@johnnywalker9067]

brilliantly explained! Chapeau! I do have a question though: In the old days of cantilever rim-brakes, even though designed to have a symmetrical pressure on the rims, I usually found, that one brake-shoe would hardly move and stay close to the rims, whilst the other side would do all the travel. I think, this was due to recoiling springs to wear out unevenly. So why does the same thing happen to the pistons in hydraulic brakes (seen in your video at 3 31 minutes), when the pressure in a liquid is evenly distributed? Should the pistons in a new bike maybe get a coating of some greasy material to keep muck sticking to the outside surface?

[@joecanuck3751]

I'm no expert so take this with a grain of salt ... one issue is that the brakes can get really hot this will cause oil and grease to become more viscous and travel to where you don't want it.

[@alanlemap]

And cheap imprecise engineering. It's plastic bike parts as opposed to high end aeronautical parts. ? My guess only.... But yes, not ideal.

[@mountainbiketim]

I let the piston fallout. No bueno. Great video guys and very informative. I have these same brakes so very helpful for my situation. How often should the seals be replaced? My brakes are about 8 years old and have about 12,000 miles.

[@AngelaCastuera]

Great video. This is the problem to my hydraulic brake now. Thanks

[@robertleslie3396]

Great tips, sorted out my sticky brakes in no time

[@roncooke2188]

You should go on national world television and have everyone smile great video interesting i am still smiling 🤩

[@dineshhanda2301]

Wonderful video as usual. Thanks Calvin, thanks Trueman

[@MTBMOM]

Lazy seals lol great video!

[@akuma9132]

thank you so much for the tutorial, the inner piston was rubbing the right part of the rotors then when i did this tutorial it actually worked!.

[@KOL630]

Excellent explanation guys thank you.

[@josereneducharme142]

Good, very good, extremely good. I just bought a ph-1 p set to help subsidize the education system.

[@parktool]

Thanks Jose!

[@g.fortin3228]

great! really helpful !!! Thanks guys really enjoy the maint. tutorials.

[@CBFREE]

Thanks for a brilliant explanation of Hydraulic Pistons with lazy seals. What about if they are not just lazy and they are dead seals and you want to replace them?